Candiru açú is also used on occasion, however according to some researchers[1] this name is primarily used for other species of the genus Cetopsis including C. coecutiens and C. gobioides.

[2] The name Candiru is shared by Vandellia cirrhosa, a parasitic catfish from the family Trichomycteridae which is otherwise unrelated to members of the Cetopsidae.

In addition to them C. candiru also possesses teeth on the vomer which share their incisiform morphology with those of the premaxilla and are likewise arranged in a single curved row.

The smallest specimen showing all of these traits measured 145 mm (5.7 in) in standard length (tip of the skull to the end of the hypural plate).

[4] Cetopsis candiru is a carnivorous fish and commonly described as a voracious feeder, making use of powerful jaw musculature and a nearly continuous cutting surface of the incisiform dentition.

Due to these habits carcasses that were fed on by C. candiru oftentimes appear almost entirely skeletonized, but retain cartilage, eyeballs and tight skin.

[2] The role of these fish as important aquatic scavengers is highlighted by their prominent appearance in forensics around the Amazon, being well known to even feed on dead human bodies found in the various rivers of northern South America.

[5][4] At least one confirmed report tells of a single Cetopsis attacking a living child, although the exact culprit could not be determined between the two carnivorous species C. candiru and C.

[6] Other reports mention Cetopsis candiru feeding on live fish caught in gillnets or hooked by fishermen.

In 1839 Cetopsis spixii was introduced in an attempt to replace the prior name and in 1862 C. candiru was chosen to serve as the type species of the newly erected genus Hemicetopsis.

Additionally, all three species are highly distinct, having each been placed in different genera at varying points in the past (Hemicetopsis, Cetopsis and Bathycetopsis).

The idea that they form a monophyletic group within Cetopsis is well supported and comparison between adults of C. oliveirai show that the species appears much like juveniles of C. coecutiens.